#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
int main()
{
	int num = 0;
	scanf("%d", &num);
	num /= 10;
	switch (num)
	{
	    case 10:
	    case 9:
		    printf("A");
		    break;
		case 8:
			printf("B");
			break;
		case 7:
			printf("C");
			break;
		case 6:
			printf("D");
			break;
		default:
			printf("E");
			break;
	}
	return 0;
}